Circuit breaker with current-limiting fuses and missing fuse interlock



Z. J. DRAGAR ETA!- CIRCUIT BREAKER WITH CURRENT-LIMITING Sept. 22, 1970 3,530,406

AND MISSING FUSE INTERLOCK FUSES 5 Sheets-Sheet 1 Filed Nov. 27, 1968 H I om h F a w h 1 w L q Ft w I 61 1 9 N W/A.///// m 5 I we fi l A 8 m N O o O Q- l P N m9 f m mm? .I m: II m p Mfr L 1 E A .9

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CIRCUIT BREAKER WITH CURRENT-LIMITING FUSES AND MISSING FUSE INTERLOCK 5 Sheets-Sheet 2 Filed Nov; 27. 1968 8 v v Q 2 m a m //4 7 5 5 5 W. 7/: m 4 3 2 E 3 Ma 2 3% W 7 2 a w a 3d F l l 25 5 Mm. 8 83 2 3 a 9 3 52 7 7 7 3 90 B 9 i I 9 mo Q 8 D 1 m Q H 2 5 v. I 8 @UDW uw 5 B 9|. I 6 3 5 MM m a y 3 5 o 7 9 a A S j 7 7 7 9 6 9 B 6 \lhw 9 Sept. 22, 1970 DRAGAR ETAL 3,530,406

AKER WITH CURRENT- LIMITING FUSES ERLOCK CIRCUIT BRE AND MISSING FUSE INT 5 Sheets-Sheet 3 Filed Nov; 27; 1968 FIGS.

Sept. 22, 1970 z. J. DRAGAR EIAL 3,530,406 I CIRCUIT BREAKER WITH CURRENT'LIMITING FUSES AND mssme FUSE INTERLOCK FIG 5 Sept. 22, 1970 z, DRAGAR ETAL 3,530,406

CIRCUIT BREAKER WITH CURRENT'LIMITING FUSES AND MISSING FUSE INTERLOCK Filed Nov. 27. 1968 5 Sheets-Sheet 5 H j: m L u h mmw o mm A 3 H M do;

United States Patent 06 ice 3,530,406 CIRCUIT BREAKER WITH CURRENT-LIMITING FUSES AND MISSING FUSE INTERLOCK Zwingle J. Dragar, Pittsburgh, and John L. Drown, Monroeville, Pa., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov. 27, 1968, Ser. No. 779,506 Int. Cl. H01h 85/48 US. Cl. 337-7 Claims ABSTRACT OF THE DISCLOSURE A fused multi-pole drawout type circuit breaker comprises a separate current-limiting fuse for each pole unit with means operable when any of the fuses blows to open the breaker, and with a missing-fuse interlock for automatically opening the breaker when a fuse is removed and for preventing closing of the breaker when any of the fuses is not in place.

BACKGROUND AND OBJECTS OF THE INVENTION In the patent to Maier et al. No. 2,883,585, there is disclosed a multi-pole drawout type circuit breaker. For certain applications of this type of breaker, it is desirable to provide current-limiting fuses in series with the contacts of the breaker to protect the circuit and the apparatus connected therein from the destructive effects of the maximum available short-circuit current. For these applications, it is desirable to provide that when one of the fuses blows the circuit breaker will be tripped upon the blowing action of the fuse, and to provide a missing fuse interlock to protect against having the breaker in the closed condition when a fuse is missing. This type of protective apparatus will protect against having single phase power supplied in the other pole units when a fuse blows or when a fuse is missing. Motors or other equipment which might continue to operate on single phase even though designed for three-phase operation could be burned out when operating on the single phase power.

Thus, an object of this invention is to provide an improved multi-pole drawout type circuit breaker having current limiting fuses in series with the contacts of the breaker with means automatically operating to open the breaker when any one of the fuses blows; with means operating to automatically open the breaker when any one of the fuses is removed; and with means preventing closing of the breaker while any one of the fuses is out of place.

Another object of this invention is to provide an improved multi-pole drawout type circuit breaker having current limiting fuses in series with the contacts of the breaker with missing-fuse interlock means for providing that the breaker contacts will be open when any of the fuses is removed.

Another object of this invention is to provide an improved multi-pole quick-detachable plug-in type circuit breaker comprising back-wall means with a circuit breaker structure supported on the front side of the back wall 'means and a multi pole current limiting fuse device mounted on the back side of the back wall means, which breaker comprises means for automatically opening the breaker when any one of the fuses blows and a missing fuse interlock to protect against having the breaker in the closed position when one of the fuses is removed.

SUMMARY OF THE INVENTION A multi-pole drawout type fused circuit breaker comprises back wall means and a multi-pole circuit-breaker structure supported on the front of the back wall means.

3,530,406 Patented Sept. 22, 1970 A plurality of conductors extend through the back wall means, and a multi-pole fuse device is supported on the back side of the back wall means with each fuse being connected into a separate one of the conductors. Quickdetachable type terminals are connected to the back terminals of the fuses and to other terminals to enable quick-detachable type connection of the fused circuit breaker in an electric circuit. Each of the fuses comprises plunger means releasable when the fuse blows. Connecting means is provided between the fuse device and the circuitbreaker structure to open the circuit breaker when any of the fuses blows; to open the circuit-breaker structure when any of the fuses is removed; and to prevent closing of the circuit-breaker structure while any of the fuses is out of place.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a circuit breaker constructed in accordance with this invention with part of an enclosure shown in broken lines to indicate the application of the circuit breaker at a drawout installation;

FIG. 2 is a side sectional view, with parts broken away, through the center pole of part of the fused breaker illustrated in FIG. 1

FIG. 3 is a side view of the fuse device seen in FIG. 1 with the interrupted condition of the fuse device shown in dot-and-dash lines;

FIG. 4 is a sectional view taken along the line IVIV of FIG. 3 with the fuses broken away for the purpose of clarity;

FIG. 5 is a sectional view taken generally along the line V-V of FIG. 4 with parts of the fuses shown in the connected position;

FIG. 6 is a perspective view of one of the levers illustrated in FIG. 1;

FIG. 7 is a view similar to FIG. 3 illustrating another embodiment of the invention;

FIG. 8 is a partial sectional view taken generally along thev line VIII-VIII of FIG. 7 with the fuses broken away for the purpose of clarity; and

FIG. 9 is a sectional view taken along the line IX-IX of FIG. 8 with parts of the fuses shown in the connected position and with parts broken away for the purpose of illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, there is shown in FIG. 1 a drawout type multi-pole circuit breaker 3 supported in a metal-enclosed switchgear housing cell, indicated in broken lines, in a manner well known in the art. The housing cell 5 comprises a pair of spaced insulating supports 7 for each pole unit. A separate conducting stab 8 is supported on each of the supports 7 and connected to bus bar means in the housing in a manner well known in the art. The housing cell also comprises a pair of tracks 9 that are engaged by wheels 10 that are supported on the sides of the circuit breaker 3 so that the circuit breaker 3 can be rolled between the connected position seen in FIG. 1 and a disconnected position wherein the breaker is disconnected from the stabs 8. The drawout breaker 3 may be supported in the housing cell 5 for movement between the connected and disconnected positions in the manner disclosed, for example, in the patent to Spencer et al. No. 2,711,452.

The circuit breaker 3 comprises back Wall means indicated generally at 11, a circuit-breaker structure indicated generally at 12 supported on the front side of the back wall means, a fuse device indicated generally at 13 supported on the back side of the back wall means and connecting means indicated generally at 15 for interconnecting the fuse device 13 and circuitabreaker structure 12 in a manner to be hereinafter more specifically described.

The circuit breaker structure 12 (FIG. 2) is of the type more specifically described in the patent to Maier Pat. No. 2,883,585. The circuit breaker structure 12 is a three-pole breaker with each pole unit comprising a separable contact structure indicated generally at 17 and an overcurrent trip device indicated generally at 18. The contact structure and trip device for each pole is mounted on a separate insulating base 19 with the bases 19 being rigidly secured to a metal panel 20. The insulating bases 19 and metal panel 20 form the back wall means 11. As can be seen in FIG. 2, each of the insulating members 19 is formed with two projections that extend through two openings 21 in the panel 20.

The contact structure comprises a stationary main contact 23, a stationary intermediate contact 24 and a stationary arcing contact 25 all supported on a terminal conductor 27 which extends through a suitable clearance opening 28 in the associated insulating support 19 to the back side of the back wall means 11. Cooperating with the stationary main, intermediate and arcing contacts 23, 24 and 25, respectively, is a movable main contact 29, a movable intermediate 30 and a movable arcing contact 31. The movable main contact 29 is mounted on a contact carry conductor 33 which is loosely supported on a movable contact arm 35 that is pivotally mounted by means of a pivot pin 37 on a conducting support 39 which is suitably fixedly supported to the associated insulating support 19. A bridging contact member 43 is biased by means of a spring 45 into engagement with the lower end of the conductor 33 and into engagement with the conductor 39.

The trip device 18 comprises an energizing coil 47 that is connected at its upper end to the conductor 39 and at its lower end to a terminal conductor 51. The terminal conductor 51, which is suitably supported on the associated insulating support 19, extends through a suitable opening 52 in the insulating support 19 to the back side of the back Wall means 11.

The stationary arcing contact 25 and the stationary intermediate contact 24 are mounted on a contact carrying member 55 that is supported for limited movement relative to the terminal on the conductor 27. The member 55 is biased to the left (FIG. 2) by a spring 57.

The movable contact structure is normaly maintained in the closed position by an operating mechanism indicated generally at 61. The operating mechanism 61 is mounted on a metallic supporting frame 63 that comprises spaced side members 65 and a connecting cross member 67. The side members 65 and connecting cross member 67 are supported on av metallic supporting platform 69 that extends across the Width of the circuitbreaker structure. The supporting member 69 is supported at the opposite sides thereof on a pair of metallic side frame members 71 that are fixedly secured to the panel 20 of the back wall means 11.

The operating mechanism 61 includes a lever 73 that is pivotally mounted on a pin 75. The lever 73 comprises a rod 79 that extends across all three pole units. Each of the contact arms 35 is operatively connected to the rod 79 by means of a separate insulating connecting member 81 that is connected to the associated contact arm 35 by means of a pivot pin 82. There is a separate insulating connecting member 81 connecting each of the contact arms 35 to the common rod 79 so that upon operation of the rod 79 the movable contact structures for the three poles are moved in unison.

An operating linkage, comprising toggle links 83, 85 and 87, is provided to hold the lever 73 and, consequently, the movable contacts in the closed position and to operate the movable contacts between open and closed positions. The toggle link 83 is pivotally connected to the lever 73 by a pivot pin 89. The toggle link 85 is connected by a knee pivot pin 91 to the toggle link 83 and by a knee pivot pin 93 to the toggle link 87. The toggle link 87 is pivotally mounted on a fixed pivot 97 on the frame 63 and has a cam member thereon.

The linkage 83, 85, 87 comprises two toggles one of which 83, 85 functions as a tripping toggle and the other 85, 87 functions as a closing toggle. The tripping toggle is normally slightly underset above a line drawn through the pivot pins 89, 93 and the closing toggle 85, 87 is normally slightly underset below a line drawn through the pivots 91, 97.

The tripping toggle 83, 85 is normally biased in a direction to cause its collapse by components of the springs 45, 57 and 59 which bias the movable contact structure for the several poles of the breaker in opening direction and bias the connecting members 81 toward the left (FIG. 2). The tripping toggle 83, 85 is normally prevented from collapsing by means of main latch member 99 that is pivoted on a pin 100 and connected by a link 101 to the knee pivot 91 of the tripping toggle; the link 101 being connected to the latch member 99 by a pivot pin 103. i

The main latch 99 is held in latching position by an intermediate latch lever 105 pivoted on a pin 107 supported on the frame 63. The latch lever 105 carries a latch roller 111 which normally engages the main latch 99 to releasably hold the main latch in holding position. The latch lever 105 at its lower end carries a latch member 113 which normally engages a part 115 of a channel-shaped member 117 that is pivoted on a pin 119 that is supported on the frame 63. The latch lever 105 and the member 117 are biased to their latching positions by a spring 121. Rigidly mounted on the right-hand end of the member 117 is a trip bar 123 which extends across all of the poles of the breaker. A separate insulating bracket 125 is mounted on the common trip bar 123 in each pole unit. An adjust-' ing screw 127 is mounted on each of the insulating members 125 for cooperating with the trip device 18 of the associated pole unit.

As long as the main latch 99 is held in latching position by the latching mechanism just described, the tripping toggle 83, 85 will, through the link 101, be held in the position shown in which the breaker contacts are held in the closed position. The closing toggle 85, 87 is normally prevented from collapsing by a shoulder support member 131 pivoted on the pin 107 and biased by a spring 133 into supporting engagement with the knee pin 93 of the closing toggle.

Fixedly secured to the front plate or cross member 67 of the frame 63 is a bearing member 135 in which is rotatably mounted a handle shaft 137 An operating handle 139 is fixed to the handle shaft 137. A disc 141 is secured to the inner end of the shaft 137, and a roller 143 is eccentrically mounted on the disc 141. The roller 143 has a dual function of engaging and actuating the channel shaped member 117 to manually trip the breaker upon movement of the handle 139 in one direction and of engaging the cam 95 on the closing toggle 85, 87 to manually close the breaker upon movement of the handle in the opposite direction.

Assuming the breaker to be in the closed and latched position with the support member 131 supporting the closing toggle 85, 87 in its extended thrust transmitting position, the breaker is tripped open by manually rotating the handle in the proper direction. During this movement, the roller 143 engages and actuates the channel shaped member 117 to disengage the latch 113 whereupon the force exerted by the springs 45, 57 and 59, biasing the contact arms 35 in opening direction is transmitted through the connecting members 81, the rod 79 and the lever 73, to cause hte tripping 83, 85 to collapse upwardly and to open the movable contacts for all of the poles of the breaker.

The closing toggle 85, 87 does not immediately collapse following release of the latch mechanism since it is held by the support 131. During the unlatching movement of the main latch 99, a cam (not shown) thereon engages the tail of the support member 131 and moves this member clockwise about its pivot 107 to disengage the shoulder on the member 131 from beneath the pin 93 whereupon the toggle 85, 87 collapses downwardly under its own weight and the weight of the moving armature of a closing solenoid which will be described later. Collapse of the closing toggle 85, 87 causes resetting of the tripping toggle 83, 85 to thrust transmitting position and also causes resetting of the latching mechanism to latching position. The operating mechanism is now in condition for a closing operation.

The circuit breaker is automatically tripped open by operation of the trip device 18 for any of the three pole units of the breaker. The trip device may be of any suitable type, preferably of the type fully described and claimed in the patent to J. B. MacNeill et a1. Pat. No. 2,669,623 which type is arranged to trip the breaker after a time delay and also instantaneously in response to overload currents of different values.

The contacts are closed either manually by operation of the handle 139 or by operation of a closing solenoid indicated generally at 145. In order to close the contacts manually, the handle 139 is moved in the direction opposite to the direction it is moved to manually trip the breaker. This movement causes the roller 143 to engage the cam 95 on the closing toggle 85, 87 to straighten the closing toggle. Since, at this time, the knee of the tripping toggle 83, 85 is restrained by the latching mechanism, the thrust of straightening the closing toggle 85, 87 is transmitted through the tripping toggle to rotate the lever 73 in a clockwise direction to close the breaker contacts. As the knee pin 93 of the closing toggle arrives at the fully closed position, the spring 133 restores the support member 131 to supporting engagement with the knee pin 93 to maintain the contacts closed.

The cricuit breaker may be closed by energization of the closing solenoid 145 which is more specifically described in the patent to Maier et a1. Pat. No. 2,883,585. The closing solenoid 145 is operated either manually or automatically by means of a closing relay and suitable switch (not shown). The closing solenoid 145 comprises a fixed M-shaped magnetic yoke 151 and a fixed magnetic core 153 mounted on the underside of the platform 69. A movable armature 155 is attached to the lower end of an operating rod 157 which extends upwardly and has its upper end pivotally connected to the knee pivot pin 93 of the closing toggle 85, 87. An energizing coil 159 is provided to energize the solenoid.

In the closed position of the breaker, the armature 155 is held in the raised position. When the breaker is tripped open, the closing toggle 85, 87 collapses downward permitting the armature 155 to move downward to its unattracted position. Thereafter, upon energization of the coil 159, the armature 155 is attracted upward and acts through the rod 157 to straighten the closing toggle 85, 87 and close the breaker.

During opening operations, the arcs drawn between the contacts 31, 25 are extinguished in an arc-extinguishing structure indicated generally at 161.

The fuse device 13 (FIGS. 1 and 3-5) comprises a metallic supporting pan 165 that is fixedly secured to the metallic panel 20 of the back wall means 11. For each pole unit a separate insulating support block 167 is secured to the supporting pan 165 by separate bolt means 169. A separate current-limiting fuse 171 is provided for each pole unit. Each of the current-limiting fuses 171 comprises a fuse body 173, a pair of fuse terminals 175, 177 extending out from opposite sides of the fuse body 173 and a releasable fuse plunger 179. Each of the fuse terminals 175, 177 is a fiat rigid conductor. The fuse terminal 175 is fixedly connected to the associated terminal conductor 27 by means of a bolt 181 that is threaded into the terminal 175. The terminal 177 is fixedly mounted on the associated insulating support block 167 by means of a bolt 183 that is threaded into a tapped opening in the block 167. The fuse 171 is constructed such that upon the occurrence of severe fault currents over a selected predetermined value, the fuse will blow instantaneously to interrupt the fault current in the associated pole unit, and the plunger 179, which is spring biased toward the left (FIG. 3) and maintained in the position seen in full lines in FIG. 3 under conditions when the fuse has not blown, will be released whereupon spring means (not shown) will bias the plunger 179 outward against the connecting means 15 to effect a tripping operation of the circuitbreaker structure in a manner to be hereinafter described. The plunger and spring means for operating the plunger may be of the type illustrated, for example, in the patent to Rawlins et al. No. 2,435,844, issued Feb. 10, 1948.

Referring to FIG. 1, it will be noted that a separate quick-detachable type terminal connector 189 is connected on the end of the fuse terminal 177, and a Separate quick-detachable terminal 189 is connected on the end of the terminal 51. The stab terminals 8 are sup ported on the insulating supports 7 that are suitably supported in the enclosure 5. The terminals 189, stabs 8 and support 7 are of the type more specifically described in the patent to Fulton et al. Pat. No. 2,647,247 issued July 28, 1953. There is a separate pair of rollers 10 mounted on each of the opposite side plates 71 of the drawout circuit breaker 3 with the rollers 10 riding on track means 9 supported on the enclosure 5 so that the circuit breaker 3 can be rolled from the connected position seen in FIG. 1 to the left to a disconnected position wherein the terminals 189 are automatically disconnected from the stab terminals 8. The means for supporting the drawout circuit breaker 3 for movement between the connected and disconnected positions in the enclosure 5 may be of the type more specifically described in the patent to Spencer et a1. Pat. No. 2,711,452 issued June 21, 1955.

The connecting means 15 (FIG. 1) interlocks the fuse device 13 with the circuit breaker 3. Referring to FIGS. 3-5, it will be noted that there is an elongated rod 193 supported on the side walls of the supporting pan 13 for pivotal movement about the axis of the rod 193. A separate elongated lever member 195 is fixedly secured to the rod 193 with each lever member 195 extending upward to a position where the member 195 engages the fuse plunger 179 of the associated fuse 171. A lever member 197 is fixedly secured to one end of the rod 193 on the outside of the supporting pan 13, and an elongated con necting member 199 (FIG. 1) is connected to the lever member 197 by means of a pivot pin 201. A lever 205 (FIGS. 1 and 6), comprising a generally U-shaped bottom portion, is pivotally connected on the breaker side plate 71 by means on a pivot pin 207 that extends through the opposite legs of the U-shaped part of the lever 205 and is secured to the plate 71. The elongated connecting bar 199 is pivotally connected to the lever 205 by means of a pivot pin 209. A torsion spring 211 (FIG. 1) supported on the pin 207, engages an extension 213 of the lever 205 to bias the lever 205 in a counterclockwise (FIG. 1) direction to thereby operate through the elongated bar 199 and lever 197 to bias the rod 193 in a clockwise direction which movement biases each of the three lever members 195 into engagement with the associated plunger 179. As can be seen in FIG. 1, an adjusting screw 217 is threaded into a tapped opening 219 (FIG. 6) in the part 213 of the lever 205 and a nut 221 (FIG. 1) is threaded on the screw 217 to fix the screw 217 in the adjusted position thereof. The trip bar 123 (FIG. 2), which is common to all three pole units of the circuit breaker, extends out to a position where the adjusting screw 217 is disposed just below the trip bar 123.

Upon the occurrence of a severe overload above a predetermined value and any of the pole units, the fuse 171 in the overloaded pole unit blows releasing the plunger 179 whereupon the plunger 179 moves from the position seen in full lines in FIG. 3 to the position seen in broken lines in FIG. 3 operating against the associated lever 195 to rotate the common bar 193 in a counterclockwise direction thereby moving the lever 197 from the position seen in full lines in FIG. 3 to the position seen in broken lines in FIG. 3. Movement of the lever 197 to the position seen in broken lines in FIG. 3 operates through the elongated links 199 (FIG. 1) to pivot the lever 205 in a clockwise (FIG. 1) direction whereupon the adjusting screw 217 engages the common trip bar 123 of the circuit breaker 3 to move the lever 117 (FIG. 2) in a counterclockwise (FIG. 2) direction about the pivot 119 to effect a tripping operation of the circuit breaker 3 in the same manner as was hereinbefore described. So long as a blown fuse is mounted in position on the fuse device 13, the plunger of the blown fuse will maintain the connecting means in the position wherein the adjusting screw 217 (FIG. 1) holds the trip bar 123 in the tripped position to thereby prevent a closing operation of the circuit breaker.

The fuse device 13 also comprises a missing-fuse interlock indicated generally at 221 (FIGS. 3-5). The missing-fuse interlock 221 comprises an elongated rod 223 that is fixedly secured to the side walls of the supporting pan 165 by bolt means 225. A separate lever member 227, for each pole unit, is pivotally supported on the rod 223. As can be understood with reference to FIGS. 4 and 5, each of the lever members 227 comprises an inverted generally U-shaped bottom part with opening means in the opposite legs thereof which receive the bar 223 with sufficient clearance so that the lever 227 can pivot on the bar 223. A separate torsion spring 229 engages one leg of the associated lever 227 at one end thereof with the other end engaging a pin 231 that is fixed to the rod 223 such that each torsion spring 229 biases the associated lever 227 in a counterclockwise (FIG. 3) direction about the rod 223. As can be understood with reference to FIGS. 3-5, each of the levers 195 extends upward between the opposite legs of the associated lever 227. With the fuses 171 in the mounted position seen in FIG. 3, each of the fuses 171 engages the associated lever 227 to maintain the associated lever 227 in the unactuated position seen in FIG. 3 against the bias of the associated torsion spring 229.

After a fuse 171 (FIG. 3) has blown to trip the circuit breaker in the manner hereinbefore described, the blown fuse may be removed by removing the bolts 181, 183 and then lifting the blown fuse out of the mounted position seen in FIG. 3. As the blown fuse is removed the extended plunger 179 of the blown fuse releases the associated lever 195 and the torsion spring 211 (FIG. 1) will bias the lever 205 in a counterclockwise (FIG. 1) direction toward a position that would release the trip bar 123 and permit closing of the circuit breaker 3. The movement of the lever 205 and trip 'bar 203 is prevented by the missing fuse interlock 221 (FIGS. 3-5). As can be understood with reference to FIGS. 3-5, when the blown fuse 171 is removed the torsion spring 229 of the associated pole unit will operate against the associated lever 227 to move the lever 227 from the unactuated position seen in full lines in FIG. 3 to the actuated position seen in broken lines in FIG. 3. During this movement, the lever 227, at the bight part 235 thereof, will engage the associated lever 195 to maintain the associated lever 195 in the actuated position seen in broken lines in FIG. 3 to thereby maintain the connecting means 15 and adjusting screw 217 (FIG. 1) in the actuated position wherein the adjusting screw 217 maintains the trip bar 123 of the circuit breaker in the tripped position to prevent a closing operation of the circuit breaker. When a new fuse, having the plunger 179 in the unactuated position, is replaced in the fuse device 13, the replaced fuse will operate against the associated lever 227 to maintain the associated lever 227 in the unactuated position seen in .FIG. 3, and with the associated plunger 179 in the retracted position the torsion spring 211 (FIG. 1) will operate against the lever 205 to maintain the connecting means 15 in the position seen in FIG. 1 with the three levers 195 positioned against the three plungers 179 in the position seen in full lines in FIG. 3, and the trip bar 123 will move back to the latching and operating position seen in FIG. 2. With the trip bar 123 in the operating position seen in FIG. 2, the'circuit breaker can be closed in the same manner as was hereinbefore described.

From the foregoing, it can be understood that if one of the fuses 171 is removed even though that fuse has not blown to interrupt the circuit, the associated lever 227 will be released to operate against the associated lever 195 to hereby operate the connecting means 15 to thereby operate the trip bar 123 to the tripped position and to maintain the trip bar 123 in the tripped position so long as a fuse is out of place.

Another embodiment of the invention is disclosed in FIGS. 7-9. As will be understood with reference to FIGS. 7-9, the levers 195, that cooperate with the fuses 171 to operate the rod .193 and lever 197 to thereby operate the connecting means 15 to trip the circuit breaker when any of the fuses blows, all operate in the same way as was hereinbefore described with reference to the embodiment disclosed in FIGS. 1-5. The missing-fuse interlock, however, has been modified from that shown in FIGS. 3-5. Thus, only the reference characters that relate to the missing-fuse interlock have been changed, and those parts that operate in the same manner as was described with reference to FIGS. 3-5 are identified by the same reference characters that were used in FIGS. 3-5. Referring to FIGS. 7-9, it will be noted that a rod 233 is fixedly supported on the side plates of the supporting pan by bolt means 235. A separate missing-fuse interlock lever 237, for each pole unit, is pivotally mounted on the rod 233 under the associated fuse 171. A separate torsion spring 239 is connected at one end thereof to the associated lever 237. Each spring 239 engages the supporting base of the supporting pan 165 at the other end thereof to bias the associated missing-fuse interlock lever 237 in a counterclockwise (FIG. 7) direction. Upon the blowing of any of the fuses 171 (FIG. 7) the released plunger 179 of the blown fuse operates against the associated lever to operate the connecting means 15 to thereby operate the trip bar .123 (FIG. 2) to trip the circuit breaker in the same manner as was hereinbefore described with reference to FIGS. 3-5. When the blown fuse 171 is removed, the associated missing-fuse interlock lever 237 is free to move, under the bias of the associated spring 239, in a counterclockwise direction from the position seen in full lines in FIG. 7 to the position seen in broken lines in FIG. 7 whereupon the lever 237, at the corner portion 245 thereof, engages the associated lever 195 to maintain the lever 195 in the position shown in broken lines in FIG. 7 to thereby maintain the circuit breaker trip bar 123 in the tripped position in the same manner as was hereinbefore described. It can be understood that when a fuse 171 is removed, the associated missing-fuse interlock lever 237 will operate against the associated lever 195 to operate the connecting means 215 to thereby operate the trip bar 123 to the tripped position and to maintain the trip bar in the tripped'position so long as a fuse is out of place.

What we claim is:

1. A multi-pole circuit breaker comprising support means, said support means comprising back-wall means, said back-wall means having opening means therein, a circuit-breaker structure supported on said support means at the front side of said back-wall means, said circuitbreaker structure comprising a pair of spaced breaker terminals for each pole unit at the front side of said back-wall means with each breaker terminal extending through said opening means to the back side of said back-' wall means, said circuit-breaker structure comprising a separate stationary contact structure for each pole unit and a separate movable contact structure for each pole unit, tie-bar means connecting said movable contact structures for simultaneous movement between open and closed positions, said circuit-breaker structure comprising an operating mechanism latched in an operating position to maintain said contacts in a closed position, a trip bar movable from a latching position to a tripped position to effect unlatching of said operating mechanism whereupon said operating mechanism automatically operates to move said movable contact structures to an open position, said operating mechanism being operable to close said contact structures only when said trip bar is in said latching position, a fuse device supported at the back side of said back-wall means, said fuse device comprising a separate fuse for each of said pole units, each of said separate fuses being removably connected to a separate one of said breaker terminals at the back side of said back-wall means, said fuse device comprising a common tripping bar structure common to all of said fuses, trip-bar actuating means supported on said circuit-breaker structure in proximity to said trip bar, connecting means connecting said common tripping bar structure with said trip-bar actuating means, said fuse device comprising a separate missing-fuse lever for each of said fuses with each of said missing-fuse levers being supported in proximity to the associated fuse and biased toward an actuating position, each of said fuses when in the mounted position thereof engaging the associated missing-fuse lever to maintain the associated missing-fuse lever in an inoperative position, upon removal of any of said fuses from the mounted position thereof the associated missing-fuse lever being released and moving automatically to an actuating position, each of said missing-fuse levers in the actuating position thereof operating through said common tripping bar structure said connecting means and said trip-bar actuating means to maintain said trip bar in the tripping position to thereby provide that said contacts will be in the open position when any of said fuses is removed.

2. A circuit breaker according to claim 1, said trip bar actuating means comprising a trip bar actuator supported for pivotal movement intermediate the ends thereof, said elongated connecting member being pivotally connected to said trip bar actuator on a first side of said pivot, said trip bar actuator comprising an actuating part extending from the opposite side of said pivot for engaging and actuating said trip bar.

3. A circuit breaker according to claim 1, said pairs of spaced breaker terminals of said circuit-breaker structure comprising a first breaker terminal and a second breaker terminal for each pole unit with said first breaker terminals being aligned in a first row and with said second breaker terminals being aligned in a second row, each of said fuses comprising a fuse body with a pair of spaced fuse terminals at opposite ends of the fuse body means removably connecting one of the fuse terminals of each of said fuse with the associated first breaker terminal, a separate quick-detachable type terminal connector connected to the other fuse terminal of each of said fuses, and a separate quick-detachable type terminal connected to each of said second breaker terminals whereby said circuit breaker may be moved into and out of quick-detachable type connection with quick-detachable type connectors of an enclosure.

4. A multi-pole circuit breaker comprising support means, said support means comprising back-wall means, said back-wall means having opening means therein, a circuit-breaker structure supported on said support means at the front side of said back-wall means, said circuitbreaker structure comprising a pair of spaced breaker terminals for each pole unit at the front side of said back-wall means with each breaker terminal extending through said opening means to the backside of said back-wall means, said circuit-breaker structure comprising a separate stationary contact structure for each pole unit and a separate movable contact structure for each pole unit, tie-bar means connecting said movable contact structures for simultaneous movement between open and closed positions, said circuit-breaker structure comprising an operating mechanism latched in an operating position to maintain said contacts in a closed position, a trip bar movable from a latching position to a tripped position to effect unlatching of said operating mechanism whereupon said operating mechanism automatically operates to move said movable contact structures to an open position, said operating mechanism being operable to close said contact structures only when said trip bar is in said latching position, a fuse device supported at the back side of said back-wall means, said fuse device comprising a separate fuse for each of said pole units, each of said separate fuses being removably connected to a separate one of said breaker terminals at the back side of said back-wall means, each of said fuses comprising plunger means releasable when the associated fuse blows to move from a retracted position to an extended actuating position, said fuse device comprising a common tripping bar structure common to all of said fuses, said common tripping bar structure comprising a separate lever member for each of said fuses with each of said separate lever members being positioned in proximity to the plunger of the associated fuse, trip-bar actuating means supported on said circuit-breaker structure in proximity to said trip bar, connecting means connecting said common tripping bar structure with said tripbar actuating means, upon the occurrence of a severe overload above a predetermined value in any of said pole units the fuse in said overloaded pole unit blowing whereupon the plunger of the blow fuse extends to an actuating position actuating the associated lever member to move said common tripping bar structure to a tripping position which movement operates through said connecting means to move said trip bar actuating means to the tripping position during which movement said trip bar actuating means moves said trip bar to the tripping position to effect automatic opening of said contact structures, said fuse device comprising a separate missing-fuse lever for each of said fuses with each of said missing-fuse levers being supported in proximity to the associated fuse and biased toward an actuating position, each of said fuses when in the mounted position thereof engaging the associated missing-fuse lever to maintain the associated missing-fuse lever in an operative position, and upon removal of any of said fuses from the mounted position thereof the associated missing-fuse lever being released and moving automatically to ma actuating position to maintain said common tripping bar structure in the tripping position whereby when any of said fuses is missing said common tripping bar structure will be maintained in the tripping position to thereby prevent a closing operation of said circuit-breaker structure.

5. A circuit breaker according to claim 4, said trip bar actuating means comprising a trip bar actuator supported for pivotal movement intermediate the ends thereof, said elongated connecting member being pivotally connected to said trip bar actuator on a first side of said pivot, said trip bar actuator comprising an actuating part extending from the opposite side of said pivot for engaging and actuating said trip bar.

6. A circuit breaker according to claim 5, said trip bar actuator comprising adjustable actuating means adjustable to permit adjustment of the interaction between said trip bar actuator and said trip bar.

7. A circuit breaker according to claim 4, each of said missing-fuse levers upon movement to the actuating position thereof engaging the associated lever member to maintain said common tripping bar structure in the tripping position.

8. A circuit breaker according to claim 4, said trip bar actuator comprising an adjustable actuating part ad-' justable to adjust the interaction between said trip bar actuator and said trip bar.

9. A circuit breaker according to claim 4, each of said fuses comprising a fuse body and a pair of fuse terminals at opposite ends of said fuse body, means removably connecting one of each of said fuse terminals with the associated breaker terminal, and a quick-detachable terminal connected to the other fuse terminal of each of said fuses.

10. A circuit breaker according to claim 4, said pairs of spaced breaker terminals of said circuit-breaker structure comprising a first breaker terminal and a second breaker terminal for each pole unit with said first breaker terminals being aligned in a first row and with said second breaker terminals being aligned in a second row, each of said fuses comprising a fuse body with a pair of spaced fuse terminals at opposite ends of the fuse body,

means removably connecting one of the fuse terminals of each of said fuses with the associated first breaker terminal, a separate quick-detachable type terminal con- References Cited UNITED STATES PATENTS 3,118,991 1/1964 Scott 327-7 2,883,585 4/1959 Maier et a1. 317-22 BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant Examiner 

